1. Field of the Invention
The present invention relates to a method of driving at least one compressor of an air distillation unit which delivers oxygen and/or nitrogen and/or argon to an industrial unit producing steam, this method being of the type in which, in the steady state, the compressor is at least partly driven by steam expansion means with production of external work, said means being supplied with steam coming from said industrial unit, this steam being introduced into an inlet of said expansion means.
2. Related Art
Certain industrial processes that consume oxygen and/or nitrogen and/or argon, such as synthetic hydrocarbon processes (referred to as gas-to-liquid or GTL processes), are exothermic and generate steam. When the pressure and/or the temperature of this steam make it unusable on the site, the steam is generally utilized as a drive supply, via a steam turbine, of at least one compressor of the air distillation unit that produces oxygen. The steam turbine may be a backpressure turbine, exhausting at a pressure above atmospheric pressure, or a condensing turbine, exhausting at a pressure below atmospheric pressure and associated with a water condenser, cooled by water or by the ambient air, and with a pump for recycling the water back into the steam production boiler.
However, the steam is fully available only in the steady state, which poses the problem of starting up the entire plant.
EP-A-0 930 268 discloses an air separation apparatus whose main compressor is coupled to an electric motor and a steam turbine that receives steam at two different pressures. During startup, the main compressor and the electric motor operate using electricity generated by a gas turbine.